Foliar Feeding 101
- Is foliar feeding the same as foliar spraying? Yes!
- Should I foliar spray cannabis? Yes!
- Can I foliar spray cannabis in vegetative and bloom phases? Yes! But only up to 14 days in bloom.
- Why can’t I foliar spray all through bloom? You risk premature browning of pistils and bud mold!
- Should I always add a wetting / delivery agent to my foliar spray? Yes! Saturator is designed to make nutrients, pesticides and fungicides more effective when sprayed on to leaves!
- Can I foliar spray clones or cuttings? Yes! But make sure to use a dilute spray!
- Will foliar spraying correct visible elemental deficiencies fast? Yes!
- Can I replace root feeding with foliar spraying? No! It’s best to do both together.
- How often should I foliar spray my plants? Once a week in fine. See our feed charts.
- What’s the best pH for foliar spraying? 6.0 - 7.0 is a good pH range.
- Should I spray the top and bottom of my leaves? Yes!
- How much should I foliar spray on the leaves? Just until you get a slight runoff.
When plants are faced with conditions of limited or unbalanced media nutrient availability or sudden elemental deficiencies due to pH fluctuation etc, feeding plants conventionally through the roots may not provide nutritive repair rapidly enough. In these situations, an alternative fast-acting method of providing the much needed nutrients required is called for. Foliar feeding or spraying is a technique in which nutrient solution is applied directly to the plants leaves and is the best method for achieving this rapid nutrient absorption into the plant. While being the center of much debate, foliar feeding has been shown scientifically to significantly improve plant health and yields through the increased absorption of essential elements.
Definitive evidence supporting the benefits of foliar nutrient applications arose in the early 1950’s through the work of H.B Tukey and S.H. Wittwer, et al. at Michigan State University. Their studies included radioisotope tagging of several essential plant nutrients which were then applied via foliar and root methods. The results were astonishing - the efficiency of nutrient use for foliar applications was nearly 95% compared to only 10% efficiency observed in root applications. The translocation (movement) of these radioisotopes throughout the plant was observed at a rate of approximately 1 foot per hour.
In 2005, Dutch Master scientists, in conjunction with UBC (University of British Columbia) scientists, radio tagged various size carbohydrate molecules and both root and foliar fed them to plants viewing the translocation of these tagged molecules using fluorescent imaging. We proved that molecular size uptake can be restricted via the root fed model, whereas, much larger molecules were able to be introduced through the leaves. We also proved that when a proprietary wetting / delivery agent like Saturator was combined with a typical nutrient regime and either root or foliar fed to a plant, it increased nutrient absorption exponentially, elementally saturating at a cellular level - typically resulting in healthier, faster growing plants!
Further research on foliar applications sought to identify the mechanism of action / transport, which is still being understood to this day. Initially, structures called ectodesmata were believed to be the primary transport mechanism for foliar-applied nutrients, which was later revoked. Stomatal transport was the likely mechanism, however many essential nutrients have been shown to be absorbed through the cuticle layer of the leaf. Thus a divide arose between the belief that the stomata was responsible for nutrient transport across leaf tissue and that permeation of the cuticle layer, to a certain degree, was responsible for this transport. Current research indicates that these 2 systems are both responsible for foliar nutrient absorption and work in parallel to achieve this.
There are still many factors that affect foliar nutrient applications such as humidity, temperature, plant physiology, and concentration. High humidity, for example, has been shown to directly affect foliar applications by decreasing the rate of evaporation - thereby allowing droplets of nutrient solution to have increased time on the leaf surface resulting in increased overall absorption. Also, environments with higher relative humidity induce swelling of the cuticular membrane, which decreases the hydrophobicity of the cuticle layer - directly increasing the absorption of hydrophilic compounds (i.e. nutrients dissolved in water).
The anatomy of the leaf structure also plays a critical role in foliar feeding successfully - as the location of the components required for transport needs to be known during application. Research has indicated that the bottom of leaves (for many crops) contains the most stomata per square inch and a thinner cuticle layer than the top surface of leaves. While the top leaf surface does in fact absorb nutrients from foliar applications, it is advisable for many crops, including cannabis, to spray both leaf surfaces with the heaviest concentration of the application being on the bottom.
Age of leaf tissue also dictates nutrient absorption capabilities, with new growth leading the way in nutrient absorption over old growth. Old growth is generally lacking in relative metabolic activity and has less structures necessary for nutrient transport, making this plant tissue less than optimal for foliar applications.
Because of water’s tendency to take a form exhibiting the least surface area possible, nutrient and pesticide sprays often bead and roll off foliage. This greatly reduces the effectiveness of the foliar application, as contact time and area are critical for optimal utilization. To overcome this surface tension obstacle, particular agents are employed to increase the amount of contact surface area - called surfactants. Short for “surface active agents”, surfactants eliminate the layer of air that forms between the leaf surfaces and the foliar solution. This allows for a substantial increase in ionic movement through the stomata and cuticular membranes. Dutch Master Commercial Edition Saturator is a unique, scientifically proven surfactant particularly formulated to provide maximum leaf saturation of foliar applications (nutritive, pesticidal or fungicidal), greatly increasing all of the benefits of feeding through leaf tissue directly.
Each of Dutch Master’s foliar products add specific benefits to your foliar application to maximize plant potential. For accelerated cash crops, our scientists recommend a weekly foliar feed regimen utilizing Sila-Guard (for stronger, more pest resistant plants capable of more efficient CO2 usage), Cal-Mag (for increased cellular division and strength, and stress resistance), Trich-XL (to ensure maximum trichome health, development and potency), and of course the wildly famous surface active wetting / delivery agent - Saturator. This weekly regimen should be followed up to the second week of flower (approximately budset). By adhering strictly to the official foliar feed charts provided by Dutch Master, you can ensure the best possible results and witness growth from your favorite strains like you’ve never seen before - guaranteed!